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spaceman spif 07-29-2012 03:32 PM

Venting bathroom fan via soffit
I recently started feeling hot attic air pouring into my bathroom through the fan. I climbed in the attic and found the flexible duct had disconnected from the fan, allowing attic air to pour right in. I also found the air flap in the fan didn't close off well, allowing the air to pour in. And I also found the exhaust end of the flex duct was just laying in the attic.

I fixed the flap so it would close and reconnected the flex duct to the fan. But now I'm wondering where to connect the outlet end of the flex duct. I can vent the exhaust duct through the soffit, but I decided to read up before doing this.

From what I've read some say it's fine, others say it's a bad idea as the warm, moist air from the bathroom can come out and then go right back into the attic via the soffit. But I question that argument because the outdoor air on a hot, humid day can also enter through the soffit, so what is the difference?

So asking you all - what are your opinions on running a bathroom vent out the soffit?

spaceman spif 07-29-2012 03:51 PM

Forgot to mention that there is already a ~3" diameter hole cut in the soffit where the exhaust duct could connect. Looks like the hole was cut for a pipe that is no longer there.

So if running through the soffit is okay, a good bit of the work is already done. But if it's not okay, I need to permanently cover that hole with something else...because the birds and squirrels sure do like my attic!

TopTechnician 07-29-2012 03:54 PM

I love your screen name, Spif! ;)
It's okay to vent through the soffit. They make special vent terminations for this purpose that will look a whole lot better than just sticking the pipe through the hole.

stickboy1375 07-29-2012 03:57 PM

12 Attachment(s)
Soffit is okay, but you need a vent cap like below...$

I would highly recommend using insulated flexible duct to your fan as well. This will help tremendously...

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